spiasm.h File Reference

Fast spi driver
Uses PASM from xSPIAsm.spin, modified from SPI_Asm.spin propeller tool library object. More...

#include "simpletools.h"

Go to the source code of this file.

Data Structures
struct	spi_struct

Macros
#define	_Title_   0
	**************** SPI Modes ****************
#define	MPRE   0
	Rx Most Significant Bit first - data valid before clock.
#define	LPRE   1
	Rx Least Significant Bit first - data valid before clock.
#define	MPOST   2
	Rx Most Significant Bit first - data valid after clock.
#define	LPOST   3
	Rx Least Significant Bit first - data valid after clock.
#define	LFIRST   4
	Tx Least Significant Bit first ; data valid after clock.
#define	MFIRST   5
	Tx Most Significant Bit first ; data valid after clock.

Typedefs
typedef struct spi_struct	spia_t
	Data type for struct.

Functions
spia_t *	spi_start (int clockdelay_ns, int clockstate)
	Starts the spi cog, loads ClockState and ClockDelay PASM variables. More...
void	spi_stop (spia_t *device)
	Stop and Release Cog. More...
void	spi_out (spia_t *device, int DQ, int CLK, int MD, int BIT, int VLU)
	Send data to SPI device. More...
int	spi_in (spia_t *device, int DQ, int CLK, int MD, int BIT)
	Receive data from SPI device. More...

Detailed Description

Fast spi driver
Uses PASM from xSPIAsm.spin, modified from SPI_Asm.spin propeller tool library object.

Author

Tom Montemarano

Version

0.5

Copyright

copyright (c) Tom Montemarano 2014, All Rights MIT Licensed

Modifications:

• Uses 'command' with PASM to load ClockDelay and ClockState variables into cog.
• spi_start parameter 'clockdelay_ns' is in nanosecs and function calculates ClockDelay value.
• device->command is either 0 or packed with 2 or 3 numbers to be used by pasm.
• command = 0 – pasm in idle loop.
  • In spi_start:
    1. the number 4 is shifted left 16 bits to indicate 'startup'.
    2. the ClockDelay value is shifted left 2 bits.
    3. the ClockState value is in bit 0. All 3 values are or'd.
  • In spi_in the number 2 is shifted left 16 bits, this is or'd with the address of the Dpin.
  • In spi_out, the number 1 is shifted left 16 bits, and or'd with the address of the Dpin.

Function Documentation

int spi_in	(	spia_t *	device,
		int	DQ,
		int	CLK,
		int	MD,
		int	BIT
	)

Receive data from SPI device.

Parameters

*device	SPI Device ID returned by spi_start
DQ	Data in pin
CLK	Clock pin
MD	SPI SHIFTIN Mode (0, 1, 2, 3)
BIT	Number of bits to receive

Returns

Value sent by SPI device

void spi_out	(	spia_t *	device,
		int	DQ,
		int	CLK,
		int	MD,
		int	BIT,
		int	VLU
	)

Send data to SPI device.

Parameters

*device	SPI Device ID returned by spi_start
DQ	Data out pin
CLK	Clock pin
MD	SPI SHIFTOUT Mode (4 or 5)
BIT	Number of bits to send
VLU	Data Value to send

spia_t* spi_start	(	int	clockdelay_ns,
		int	clockstate
	)

Starts the spi cog, loads ClockState and ClockDelay PASM variables.

Parameters

clockstate	- 0 = start clock low, 1 = start clock high
clockdelay_ns	- Actual delay in nanoseconds (1000ns = 1 usec), not less than 300ns. This is different than the spin object that uses ClockDelay. spi_start calculates the ClockDelay value from clockdelay_ns. ClockDelay = ((clockdelay_ns) - 250ns)) / 50ns. e.g. for 2 usec (i.e. 2000 ns): ClockDelay will equal 35. for 1 usec ClockDelay will equal 15.

Returns

spia_t pointer for use as an identifier for spi functions

void spi_stop

(

spia_t *

device

)

Stop and Release Cog.

Parameters

*device

SPI Device ID returned by spi_start